We propose to acquire an SGI Onyx 3400 supercomputer, capable of state-of-the-art performance in simulation, computation and visualization, to upgrade a well-established Computational Core facility, and to provide the basic computational engine of the recently formed Advanced Imaging Program at Mount Sinai School of Medicine (MSSM). A recent initiative at MSSM to expand the imaging and computational sciences, together with the ongoing evolution of bandwidth and resolution in imaging technology is generating enormous multi-dimensional datasets (on order 20-4090 GB in this proposal) whose analysis, reconstruction and visualization demands computational speed and memory far exceeding available resources. No machine current exists at MSSM for visualization and simulation of large multi- dimensional datasets in excess of approximately 1 GB. The Advanced Imaging Program is a distributed program that incorporates all levels of microscopic analysis, MR microscopy and several imaging modalities in humans and animal models, and promotes the exchange of ideas and collaborative initiatives amongst researchers that is essential to ensure the continued advancement of scientific research at MSSM. In addition to the major user group, the supercomputing/visualization facility will be available to collaborators at neighboring institutions (MYU, SUNY Stony Brook), providing a centralized resource for high-performance computational and visualization, and fostering interdisciplinary and inter- institutional collaborations amongst the wider New York research community. Each of the research programs described by the major users of the proposed Onyx 3400 supercomputer is current constrained either by computational limitations or by unmet visualization requirements that are beyond the scope of any available computational resources. The projects that will benefit from the proposed equipment represents a broad range of basic scientific and clinically related studies, which heavily utilize well-developed imaging facilities at MSSM, but are lacking a centralized computational and visualization facility. The acquisition of the proposed supercomputer will have a major impact on research at MSSM by establishing a common facility by computationally intensive analysis and display of high-resolution imaged data. As a shared computational facility, it will promote development and exchange of novel quantitative imaging and image analysis tools between the major users, and foster multi-disciplinary interactions with investigators from diverse areas with common computational and visualization requirements.